Charles Saatchi has sold Marc Quinn's Self, a cast of the artist's head in nine pints of his own frozen blood, one of the works most fiercely emblematic of Britart.

Saatchi made £1.5m from the sale - representing a decent return on his investment, since he bought the work in 1991 for a reputed £13,000. The work, sold to an American collector, is now lost to the UK.

Quinn's work - to some repellent, to others gorgeously rich with its deep rubiginous colouring and mottled patina - caused a stir when revealed to a large audience at the Royal Academy's Sensation! show in 1997. Three years ago, there were delicious rumours, hotly denied, that builders employed to refurbish Saatchi's kitchen in honour of his celebrity chef wife, Nigella Lawson, accidentally melted it by unplugging its electricity supply. It must be kept at -12C (10F).

The sale will fuel rumours that Saatchi is offloading his entire Britart collection. In December, Damien Hirst's formaldehyde-pickled shark fetched £6.25m. He has sold at least 12 other works by the same artist, and four Ron Muecks, including his Dead Dad (a horribly realistic sculpture of his late father).

The works have been sold, by and large, to the US, where Britart is increasingly popular, with shows by such artists as Sarah Lucas and Gary Hume displayed in the most fashionable galleries in New York's Chelsea district. Hirst is fetching particularly good prices. It also reflects a relative paucity of big-hitting, UK-based contemporary art collectors.

It is clearly a good time for Saatchi to be selling, especially as he does not seem to believe in the Young British Artists' staying power, telling the Art Newspaper they might be "nothing but footnotes" in a century's time.

It would not be the first time Saatchi has sold off nearly an entire collection. In the 80s he sold most of his postwar American art, including works by Warhol and Koons, which some see as a worse loss to the UK than the potential disappearance of his Britart holdings.

The move also signals that Saatchi's eye is turning towards painting, as seen in the current Triumph of Painting show at the Saatchi Gallery, and the drift of taste towards German work (Wolfgang Tillmans, Jürgen Teller, Gerhard Richter et al) and the next big thing: art from China.